Paris Opera LA SOURCEundated, tissue, stereoscopic 'slide'

the 'slide' scanned here is captioned LA SOURCE, with little further identification.
the same picture is included in an issue of DANCE INDEX ("The Dance Criticisms of Carl Van Vechten") for an entry entitled Leo Delibes, the caption identifies the picture as "Act one," but i wonder if this is correct. The seemingly dried up 'stream' might just as well show the final scene, when the 'source' ceases to flow. additionally, the caption says the photo shows a 'stage model, ca. 1870' which may or may not be correct.
i assume the figures at the top of the stairway are Djemil and Nourreda, with the fairy of the spring, Naila, nowhere in sight, though her sylph sisters are seen languishing around the dry spring.